Reflector-shade for artificial lights.



No. 763.689. PATENTED JUNE 28, 1904.

0. A. MYGATT.

REFLECTOR SHADE FOR ARTIFICIAL LIGHTS;

APPLICATION FILED NOV. 19, 1903- NO MODEL.

1145 Noam: vzrzns co. Pnoru-uruu, WASNINGTQN. n. c.

No. teases.

Patented June 28, 190

PATENT OFFICE.

OTIS A. MYGATT, OF NEW YORK, N. Y.

REFLECTOR-SHADE FOR ARTIFICIAL LIGHTS.

SPECIFICATION forming part of LettersPatent No. 763,689, dated June 28, 1904.

Application filed Nove b '19, 1903. Serial No. 181,831. (No model.) i

To all whrmt it warty concern:

Be it known that I, OTIS A. lVIYGAT'La citizen ofthe United States, residing at New York, in the county of New York and State of New York, have invented certain new and useful Improvements in Reflector-Shades for Artificial Lights, of which the following is a specification.

This invention relates to shade-reflectors for artificial lights.

The object of the invention is to produce from a single piece of glass a prismatic reflector which shall reflect practically all the light-rays from an electric lamp or other light and which shall send such light-rays in the desired direction partly by reflection of light-rays which pass through a part of the reflector and are reflected in the desired general direction and inpart by reflection of rays which do not pass through and out of the glass; also, to form an improved combination of reflecting and difl'using surfaces,

for light distribution.

The invention is a modification of and addition to the invention described in my application, Serial N 0. 134,332, filed December 8, 1902.

Figure 1 is a vertical section of a shade-reflector as applied to an incandescent lamp, showing also the course of some of the lightrays and indicating other matters hereinafter referred to. Fig. 2 is a side elevation of a shade-reflector, illustrating the present invention. Fig. 3 is a diagram or enlarged section showing general direction of single reflection of light-rays according to the present invention. Fig. 4 is a diagram or section showing lines of double reflection. Fig. 5 is a diagram illustrating the direction of light-rays through a neck not provided with prisms. Fig. 6 is an elevation showing position of my improved reflector-shade in projecting light horizontally. 4

Let A indicate the body or neck of a reflector, and B the bell-mouthed part thereof. These are subject to great modifications of size and form; but the general construction includes a comparatively small annular portion, which surrounds the upper part of the lamp or light, and a flared, bell-mouthed, or parabolic portion, which surrounds the lower part of thelight. The terms upper and lower are used relatively to the illustration. The reflector and light may be placed in any position, horizontal or otherwise, but are usually about in the relative position illustrated when used in combination with an incandescent electric light. The reflector depends for its relative action on external prisms.

In pressing prismatic reflectors and shades, which is the only known practical way of producing such articles from glass, it is desirable to make the reflector as thin as possible for many reasons-among them to save expense, to save weight, to escape the loss of light which results from transmission through large masses of glass, and other reasons.

It is known to glass-workers that glass 111 plastic or molding condition does not flow readily, as molten metal would do, but must be forced into the extremities of the mold in viscous condition from a mass placed near the center of the mold. Glass becomes more refractory as it flows, and a large molded article is necessarily much thicker than a small one. In the form of reflector illustrated if the parabolic portion a b were removed further from the bulb--say to the line a Z)-it would necessarily be not only much larger in diameter, but also much thicker, and would necessarily be two or three times heavier. If further removedsay to about the position commonly occupied by a metallic or silvered reflectorits weight would be still further in creased in almost geometric proportion to its size.

In the construction of incandescent electricsay the point 0-it is not actually true, as

considerable light emanates from the entire length of the filament-say to the support k.

By making the reflector with a neck A the parabolic or other flared portion B (small and close to the bulb) can be made as eflective as would be the much heavier reflector made as large as would be a reflector having its equivalent arc OI] the much longer line a 7). Besides being lighter and cheaper the reflector with narrow neck A can be much more conveniently applied and held in place by any usual form of holder, which usually attaches to the collar C of the reflector and to the socket E of the lamp.

The flared part B of the reflector, as shown, is wholly covered with reflecting-prisms D. While it is not essential that the entire surface be so covered, it is found that the greatest reflection will be eifected if such be the case. The greatest effect in reflecting light by prism is accomplished when the light enters the glass-say in the direction 0, Fig. 4 strikes the outer plane of the prism at (Z at an angle of forty-five degrees, is reflected across the prism to a at an angle of ninety degrees, and again reflected in the direction 7" at an angle of ninety degrees. Such prisms I now term double-reflecting prisms, because the light-rays are twice turned from a straight line and return in a line practically parallel to the line of original direction. Prisms of this character of transparent glass can be made to reflect or throw back as much as eighty-five per cent. of the light striking them. I have been unable to construct any prisms of pressed glass which reflect all of the light transmitted to them. I have therefore adopted the term double-reflecting as being the most accurate descriptive term I am able to supply.

An advantage of having the bell-mouthed portion of the reflector covered with prisms of the character indicated at D is that such prisms are as effective for reflection as any known form of prism and are not perceptibly injured in reflective power by the presence of dust on their outer surfaces. Thus if the reflector A B be suspended from above in the position of Fig. 1 or be turned so that its mouth opens horizontally, Fig. 6, the accumulation of dust will be almost entirely on the outer ribbed surface, where it does no harm so far as reflection of light from within is concerned. This is an important matter where hundreds of lights are suspended at high elevations, as in theaters, churches, and public buildings, and the cleaning of the lights becomes a diificult work, likely to be more or less neglected. The smooth inner surface of the reflector is not likely to accumulate dust unless the mouth turns upward, a position seldom used.

I will now consider the neck or body A of the reflector. In Fig. 3Ihave indicated on a large scale the construction of a section of the wall of the neck, the prisms F being external thereto. I have stated that according to known laws the most complete reflection of a light-ray is effected when the ray encounters a plane surface at an angle of forty-five degrees. This does not apply to the surface at which the light enters the glass. A light-ray is, striking the inner surface 2' of the neck at an angle of forty-five degrees is not reflected and slightly, if at all, refracted; but striking the outer plane surface m again at forty-five degrees it is reflected at an angle of ninety degrees. Emerging at 0 if this face of the prism be at an angle of ninety degrees to the line of direction of the light-ray the ray will not be deflected, but will emerge on the line 7). By changing the angles of inclination of the prisms F the light-rays emerging from the neck or body A can be directed in almost any direction. Ordinarily the upper plane surfaces m of the prisms F will be substantially horizontal when the reflector is in the position of Fig. 1. In general it is intended that the light-rays from the neck in a reflector of the character described shall take the direction indicated at /t 0 p, Fig. 1, which is substantially parallel with the direction of the ray of in the same figurethat is, a light-ray directed to the right in Fig. 1 passing through the single or once-reflecting prisms F of the neck A takes substantially the same final direction as a light-ray directed to the left in the body B and twice reflected by the doublereflecting prisms D without having passed through the glass at all. The upper surfaces on of prisms F are not injured materially, if at all, by the presence of dust. The lower surfaces 0 being under the overhang do not accumulate dust under ordinary conditions. Dust on the faces 2' or 0 would interfere with the transmission of light. Dust on the surfaces on or on prisms D does no harm, because such surfaces are not intended to transmit but to reflect light.

In Fig. 5 I illustrate diagrammatically the direction of light-rays through a neck A not provided with external prisms. Whether the rays pass directly through the glass, as at s, or are reflected, as at t, they move upward and are lost so far as the useful direction is concerned.

The single-reflecting prisms F on the collar A not only reflect the light in the useful general direction of the rays from the bell-mouth, but they impart an attractive appearance to that part of the reflector. Some of the rays may be thrown on the outside of the prisms D, as shown at we, and as these rays strike at various angles an iridescent or prismatic effect is produced under some circumstances.

I use the term single-reflecting prisms as distinguishing the prisms placed circumferentially about the neck of the reflector-shade, through which part of the shade and through the prisms the light from the lamp passes to the outside of the reflector-shade, (by these prisms most of the light which strikes them from within is once reflected or refracted, but is not to any considerable extent thrown back into the interior of the shade-reflector,) and by the term double-reflecting prisms I refer to the prisms which overlie the flaring body of the shade-reflector and which throw back a very large proportion of the light which strikes them from within into the interior of the shade-reflector, (see Fig. 4,) and this light is emitted from the bell-mouth of theshadereflector.

Reflectors of the general character of the reflector A B are largely used for lighting and for decoration in the position shown in Fig. 6 to project the light horizontally. Such a light, with the bulb and reflector composed of the clearest glass, becomes dazzlingl y brilliant I and painful to the eyes when seen directly from the frontthat is, looking into the bellmouth of the reflector. To obviate this objection and to soften the light, the incandescent lamp G is clear at its upper part and is provided with a diffusing-surface I, such as an etched or ground or an opaline or similar surface. The ray f reflected back from the reflector and into the lamp-bulb is diffused or deprived of much of its glaring intensity and is broken up in the direction 9. The light-rays not reflected, but passing through the diflusing-surface I, are also diffused. A light of this kind when viewed from below, as in Fig. 1, or horizontally, as in Fig. 6, does not expose the filament of the lamp to the eye, and when observed at an angle only part of the filament can be seen. This combination of reflector and shade is exceedingly simple and useful.

I do not claim herein the reflector having 'its bell-mouthed body covered with doublereflecting prisms D and its neck covered with refracting-prismS, as claimed in my application referred to and in which a part of this invention is disclosed.

hat I claim is 1. A reflector of glass having an annular neck and an outwardly-flaring mouth, the outside surface of the mouth portion being practically covered with double-reflecting prisms, and the outside surface of the neck practically covered with single-reflecting prisms.

2. A reflector of glass having a neck and an outwardly-flaring mouth internally smooth, the neck being covered externally withsinglereflecting prisms, and the body externally covered with double-reflecting prisms.

3. A reflector, of glass, having a neck externally covered with circumferential prisms having their upper faces in planes parallel with the planes of the ends of the reflector and having a body of larger diameter than the neck, flared outwardly, and substantially covered externally with double-reflecting prisms. 4:. In a reflector of glass, an open-mouthed portion having external double reflecting prisms, and a neck having external single-reflecting prisms, combined with an incandescent-lamp bulb substantially inclosed within the reflector, and having its upper portion of clear uncovered glass and its lower portion covered by a light-diffusing surface.

5. The combination, in a glass reflector, of an outwardly flaring part having external double-reflecting prisms, and a neck part having external single-reflecting prisms, some of the latter arranged to reflect light after passing through the neck onto the outer surface of the mouth part.

In testimony whereof I affix my signature in presence of two witnesses.

OTIS A. MYGATT.

Witnesses:

W. A. DoRcY, H. E. NASON. 

